Lactose Intolerance 101

If you've ever eaten too much cheese or polished off a pint of ice cream in one sitting, you probably felt sick to your stomach. Most likely, the cramping, bloating, and abdominal pain you felt were caused by your body's inability to break down lactose, which is found in most dairy products.

Known as lactose intolerance (LI), this common condition affects up to 70 percent of the world's population. LI is caused by a deficiency of lactase (the enzyme that breaks down milk sugars) and is more prevalent in some populations than others, affecting African-Americans, Native Americans, and Asians more frequently.

The condition can often result in unpleasant and embarrassing symptoms that usually begin 30 minutes to two hours after eating dairy products. The severity of those symptoms depends largely on the amount of dairy consumed and the actual amount of lactase the individual produces.


LI is not always easily diagnosed, as the symptoms mirror those of many other conditions, including irritable bowel syndrome and stomach flu. Nausea, abdominal pain, cramps, gas, flatulence, bloating, and diarrhea are the most common, but if you suspect that you may be lactose intolerant, it's best to get tested by your doctor to rule out other conditions

The hydrogen breath, lactose tolerance, and stool acidity tests are the most common methods used to measure how well the digestive system absorbs lactose and will be able to confirm a suspected diagnosis of LI.

Lactose Tolerance Test. This test measures an individual's glucose (blood sugar) levels several times over a two-hour period after they've fasted and then consumed a liquid containing lactose. Glucose levels that fail to rise indicate that the body is unable to digest lactose. Normally, lactase breaks down the lactose into glucose and galactose once it reaches the digestive system. The liver converts the galactose into glucose, causing blood sugar levels to rise.

Hydrogen Breath Test. Undigested lactose in the colon is fermented by bacteria, resulting in the production of hydrogen and various other gasses. After the intestines absorb the hydrogen, it is carried up to the lungs and exhaled. The hydrogen breath test analyzes an individual's breath at regular intervals after drinking a lactose-containing beverage. High levels indicate LI. Because cigarettes and certain foods and medications can skew test results, it is important to check with your doctor to avoid anything that could affect the accuracy of the test.

Stool Acidity Test. This test is most commonly used for young children and infants. It measures the amount of acid in the stool that is produced when undigested lactose is fermented by bacteria. Higher levels of acidity will help to confirm a lactase deficiency.

Managing Lactose Intolerance
Although there's no real treatment for the body's inability to produce lactase, the symptoms can be managed by maintaining a diet that limits or eliminates lactose-containing foods and beverages. Parents with infants and young children who have lactase deficiencies should avoid giving them formula or foods containing lactose until they are able to digest lactose.

Most adults and adolescents don't have to eliminate lactose completely, but they differ in the types and amounts of lactose-containing foods that they can handle. Tablets or liquids containing the lactase enzyme are available over the counter and are often used by those who only react to small amounts of lactose or have trouble limiting their intake. In addition, lactose-reduced milk and other dairy products can be found at most supermarkets.

LI does not have to compromise your nutrition. Milk and dairy products are filled with essential nutrients, like calcium, but these needs can still be met by taking supplements and by eating other calcium-rich foods that don't contain lactose. Examples of these are fish and leafy green vegetables.